The present invention relates to a process for producing a carbon material and a carbon/carbon composites.
Carbonaceous pitch is used as a starting material for a high-density carbon material because of a high carbonization yield thereof. However, it involves the problem of bubble formation and crack formation caused by the evolution of decomposition gas during carbonization. As a method for solving this problem there is used hot isostatic pressing (hereinafter referred to sometimes as "HIP"). But the gas evolved during carbonization will contaminate intra-furnace components such as a heater and heat insulating material, and as the case may be the HIP system may be damaged. To avoid this, in HIP for the production of carbon material, there is performed what is called canning wherein a feed material is placed in a sealed type container such as one made of glass or stainless steel. The container also serves to maintain the shape of a product being heat-treated. On the other hand, a carbon/carbon composites has unique properties such as maintaining high strength and high elasticity even at high temperatures above 1,000.degree. C. and small thermal expansion and its application to components of airospace-craft and devices, brakes, furnace materials, etc. Due to the aforesaid characteristics, carbonaceous pitch is also used as a matrix precursor for a carbon/carbon composites, and in the carbonization step of this manufacturing process there is used HIP wherein what is called canning is performed, that is, feed materials a charged into a glass or stainless steel container.
Where a closed type container is used, however, a canning step such as vacuum sealing is needed for imparting a sealing function to the container. Further, removal of the container and re-canning are necessary at the time of re-impregnation for densifying. As a result, the manufacturing process becomes complicated and the treated product may be cracked due to the internal pressure of the gas evolved or a carbon fiber fabric may be deformed due to the pressure of the container during production of a carbon/carbon composites.